Its often a big suprise to people that adding steam to food can enhance the crispiness. This is certainly the case with pork. The steam helps render the fat under the skin and makes for a super crispy crackling.
I also find that the method I use of pouring boiling water over the skin before drying and rubbing with salt and oil, really aids in the fat rendering under the skin and results in a great crispy crackling
Crush Fennel seeds and mix with other spices.
Slice through skin of pork belly at 1cm intervals using sharp knife .
Place the pork on a rack skin side up, and pour boiling water over the skin.
Dry off with a paper towel.
Turn over and rub spice mix over meat side of pork belly.
On Skin side massage in oil and sprinkle liberally with salt.
Place pork belly on solid tray near top of oven.
Select Fan+Grill 220C for 25 minutes
Change function to Steam+hot air 150C for 1 hour 30 minutes.
Then finish with Grill 270C for just a few minutes watching carefully as the skin will pop up and could burn very quickly